1. Field of the Invention
The present invention relates to a pushbutton tuner for radio sets, television sets and other apparatus, and particularly for automobile radio sets or the like. A pushbutton tuner of this type presents a plurality of pushbutton assemblies mounted on the tuner frame for in and out movement, each one of these pushbutton assemblies carrying adjustable memory means for recalling a memorized broadcast frequency when the pushbutton assembly is pushed inwardly.
2. Statement of the Prior Art Known to the Applicants
The following prior art is known to the applicants:
U.S. Pat. No. 4,030,052 (PELLETIER): the whole document. PA0 German (Federal Republic) Publication of Patent Application (OS) No. 2,614,610: the whole document.
3. Prior Art Pushbutton Tuners
Conventional pushbutton tuners comprise a plurality of pushbutton assemblies arranged side by side and parallel to each other, longitudinally slidable inside a tuner frame, and each carrying an abutment member which can be angularly adjusted around an axis which is perpendicular to the plane of the pushbutton assembly, and is associated to means for locking or unlocking same so as to adjust its angular position at will and maintain such position once adjusted. Each pushbutton assembly cooperates, by means of its abutment member, with the inclined edges of a V-shaped notch obtained in a control bar transversely arranged with respect to the pushbutton assemblies, said control bar being operatively associated to the tuner group of the radio set, so as to actually control same as a consequence of its longitudinal movement promoted by the insertion of any pushbutton assembly and by the consequent action of the abutment member on the inclined edge of the V-shaped notch.
In the known pushbutton tuners, the abutment member consists of a pin which is mounted angularly adjusted on each pushbutton assembly. Whenever a pushbutton assembly is pushed inwardly to select a predetermined frequency, the abutment pin rests, at the end of the inward movement of the pushbutton assembly, in the vertex angle of the associated V-shaped notch of the control bar. In this end position, the abutment pin normally results to be inclined with respect to the longitudinal axis of the pushbutton assembly and consequently also inclined with respect to the thrust force exerted by the pushbutton assembly. Consequently, a component of the said thrust is transmitted from the abutment pin to the control bar, in the longitudinal direction of the said control bar, and tends to longitudinally shift said control bar. As a consequence, in the pushbutton tuners of this type, the tuning cannot be very accurate, also in consideration of the fact that most of the times the pushbutton assemblies are pushed, by the user, with great force.